The advent of molecular biological techniques has led to a dramatic increase in the speed, efficiency and species resolution obtained in microbiological studies from virtually every environment on earth. While this has revolutionized the way microbiology is performed, a requirement for access to laboratory facilities and infrastructure still exists, thereby introducing a spatial and temporal separation between sample collection and analysis.
There has been an increasing need in the scientific and military communities to collect and analyze data in the field. In situ analysis holds many advantages over collecting samples, transporting them, and analyzing the samples in a laboratory. Timely analysis reduces degradation of the samples, permits more rapid feedback to the observer, and may reduce overall cost as well as improve the results of the analysis.
Toward achieving a truly portable sensor, several requirements must be kept in mind. The system must be operated on an internal battery or portable power; therefore the entire system must be conservative with its power usage in order to be operable for an extended period of time. There should be a method for giving feedback to the user, in order to verify the analysis is being performed properly. Preferably, a familiar graphical user interface (GUI) should be provided to display the data or other relevant information in real-time, this will allow the user to immediately interpret and react to the test results. In addition to displaying information, the data should be stored for later retrieval and further analysis on a desktop computer. To achieve widespread use, the system cost should be kept as low as possible. This is especially relevant for MEMS sensors, which take advantage of wafer-level processing capabilities, to reduce the cost of system components. To be truly portable and easily operated by the end user, the complete sensor assembly should be handheld.
As is known in the art, a filter fluorometer measures the ability of a sample to absorb light at one wavelength and emit light at a longer wavelength. A filter fluorometer is a good choice when sensitive quantitative measurements are desired for specific compounds. The comparative ease of handling and low cost make filter fluorometers ideal for dedicated and routine measurements. A fluorometer provides a relative measurement and can be calibrated with a known concentration standard or correlated to standard laboratory methods to produce quantitative measurements. Fluorometers are utilized in molecular biology for the detection and measurement of a variety of elements. In a particular application, it is known to use a filter fluorometer as a nucleic acid amplification device.
Due to the temperature sensitivity of fluorescence measurements, many fluorometers include heating and cooling capabilities. Heating systems know if the art for use in fluorometers, consist of ceramic block or resistive heaters and cooling fans. These components exhibit a high thermal mass.
Common bench top instrumentation platforms, including filter fluorometers, are large and expensive, and primarily target high throughput screening laboratory analysis. Such systems offer little recourse for laboratories operating on limited budget, tight space restrictions, small sample throughput, or to technicians collecting samples in the field. Environmental and clinical applications that require nucleic acid amplification, enzymatic studies and analytical biochemical reactions, that require precise thermal control, would benefit from a portable instrumentation system designed for these applications.
System in Package (SiP) design methodology in the electrical packaging field takes advantage of the integration of high degrees of chip scale packages onto interconnect substrates to develop novel compact electronic systems. SiP has numerous advantages over other packaging design paradigms such as System on Chip (SoC) where complete electronic systems are integrated onto a single chip. Typically SiP decreases design risk, developmental time and cost compared to SoC systems as each individual component is manufactured in its own optimised process and interfering components can be more easily isolated from each other during the design and manufacturing process. Similarly SiP systems provide more flexible design which allows for easy modification to circuitry when advances in processor speeds or memory occur. SiP delivers increased functionality and performance in a small form factor for mobile applications. As such, SiP has become the leading mechanism for the miniaturization and added functionality of consumer electronics such as laptop computers, mobile phones and portable music players, however, it has not been aggressively applied in the design and miniaturization of portable scientific equipment.
Compared to traditional culturing and biochemical analysis, molecular detection techniques such as the Polymerase Chain Reaction (PCR) or Nucleic Acid Sequence Based Amplification (NASBA) have dramatically decreased the time required to analyse samples from virtually any environment. Point-of-use real-time molecular detection techniques have the potential to remove the spatial and temporal separation between sample collection and analysis that exists in standard laboratory practices. However, despite many molecular assays being adaptable to in-field use, at present the majority still reside in the laboratory, primarily due to a lack of small, cheap and portable instrumentation.
A portable hand-held heat regulated fluorometer capable of performing and detecting Real-Time (RT)-NASBA was previously developed used a commercially available infra-red heater and detector for thermal control and had relatively high power requirements. Various iterations of the instrument have been developed, however to date all have required an expensive user interface such as a personal computer or Personal Data Assistant (PDA).
Therefore, what is needed is a simplified and compact hand-held instrument to perform, detect and report a RT-NASBA reaction, as a demonstration for portable isothermal amplification and detection.